A woman shall have no more than three children. Therefore, in a marriage there shall not be more than three children, if at all.
If a man has been divorced and marries another wife, or if he has more than one wife, he may have a maximum of three children with each wife (within each marriage/partnership).
However, the prerequisite is that the parents are capable to raise the child/children in a loving surrounding and with enough nourishment for the body and consciousness, etc. etc. in order that the child/children may grow up with good health regarding psyche, consciousness and body (note by Christian Frehner: and hopefully free of addiction to any religion or other destructive doctrines, etc.).
By the way: Billy has three children with his ex-wife and one with his actual partner, plus two sons of whom he is not the biological father.
Note by CF: Of course the limit of three children per wife does not mean that each woman must have three children. There are many women who should have no children (or less than three), just as there are many fathers who should never have become father(s).
Besides, it is very advisable that there is a time span between the children of at least three years.